Time-resolved axial LIF contour plots showing multiple ion populations throughout the BHT-600 central jet. Each scan (vertical strip) is normalized by the integrated signal, with each panel normalized by the overall maximum. The corresponding time-averaged LIF and discharge current traces are reproduced to the right and below each panel, respectively. The data are repeated over three cycles for visual effect. Data are obtained from (a) $(x,z)=(−4,25)$⁠, (b) $(x,z)=(0,25)$⁠, (c) $(x,z)=(−4,20)$⁠, (d) $(x,z)=(0,20)$⁠, (e) $(x,z)=(0,10)$⁠, and (f) $(x,z)=(0,15)$⁠.